The present invention relates to improvements in apparatus for transporting stacks of paper sheets or other commodities between spaced apart first and second stations. More particularly, the invention relates to improvements in apparatus for transporting successive commodities, either continuously or stepwise, from a first station to a second station and for returning the transporting instrumentalities to the first station, upon delivery of a commodity to the second station, so as to enable the instrumentalities to engage and entrain the next commodity.
Apparatus of the above outlined character can be used with advantage in machines for the processing of stacked paper sheets, e.g., in so-called spiral binding machines wherein successive stacks of preperforated paper sheets or stacks which are perforated in the machine proper are provided with spiral binders to form therewith steno pads, exercise books, calendars or analogous stationery products. In many instances, transporting apparatus for stacks of paper sheets or the like comprise tongs with jaws which engage a stack at the preceding station and open upon completion of movement to the next-following station so as to allow for removal of the stack or for other treatment of such stack at the next-following station. The tongs is movable back and forth between two stations and the jaws are arranged to close at the preceding station and to open at the next-following station. The utilization of transporting apparatus which include tongs is advisable in machines wherein stacked paper sheets, panels, foils or the like must be transported and located with a high degree of accuracy. The same holds true if the stacks of paper sheets or the like must be subjected to one or more treatments during transport between a preceding and a next-following station. For example, preparation of stacks of paper sheets for assembly with spiral binders necessitates several preliminary treatments which must be carried out with a high degree of accuracy in order to facilitate threading of the binder into the perforations which are provided along one marginal portion of the stack. In the absence of accurate alignment of neighboring sheets or shifting of certain sheets to predetermined positions, the leader of the spiral binder would encounter numerous obstacles and would be incapable of passing through all perforations of a stack.